A few days ago, I got a notification to upgrade my iPad's IOS. When I did, I could no longer use the Set List Manager in iGigBook. Trying to start a new Set List causes iGigBook to crash, every time. I understand that a similar problem is happening with Android.
The developer needs to fix this problem quickly.

I contacted Apple Support, who recommended uninstalling and reinstalling iGigBook. This did not solve the problem, and moreover caused me to lose roughly 500 lead sheets--which I now must reinstall by the slow and clunky iTunes file sharing process. iGigBook users, DO NOT install IOS 11.2, and DO NOT uninstall iGigBook--until this problem is fixed.

A few days ago, I got a notification to upgrade my iPad's IOS. When I did, I could no longer use the Set List Manager in iGigBook. Trying to start a new Set List causes iGigBook to crash, every time. I understand that a similar problem is happening with Android.
The developer needs to fix this problem quickly.

I contacted Apple Support, who recommended uninstalling and reinstalling iGigBook. This did not solve the problem, and moreover caused me to lose roughly 500 lead sheets--which I now must reinstall by the slow and clunky iTunes file sharing process. iGigBook users, DO NOT install IOS 11.2, and DO NOT uninstall iGigBook--until this problem is fixed.

You're posting about a problem in a thread where it is stated that the problem has been fixed. Are you saying you're experiencing this problem with version 5.5?

No, this is not a similar problem with the Android version.

Also, don't uninstall any app without backing up it's data because when you uninstall an app all of the data associated with the app is deleted. If you're having a problem with iGigBook we are the people to contact not Apple because they will not be able to help you as you have discovered.